Among semiconductor devices, a power semiconductor device is used for controlling and rectifying relatively large electric power in a vehicle, such as a railroad vehicle, a hybrid car and an electric vehicle, a consumer electronic device, an industrial machine, and the like. High heat dissipation is required of a power semiconductor device since when in use a power semiconductor element generates heat. A high insulation property with respect to the outside is also required of a power semiconductor element since a high voltage more than several hundred volts is applied thereto.
Here, an IPM (Intelligent Power Module) is a module into which a power semiconductor element and a controlling semiconductor element (hereinafter briefly referred to as a controlling element) are integrated. When a lead frame is used as a wiring material in an IPM, the power semiconductor element and the controlling element are mounted on physically-separated two lead frames, respectively. Specifically, the power semiconductor element and the controlling element are mounted on die pads provided on the lead frames, respectively. The power semiconductor element is electrically connected to the lead frame via a power metal thin wire, and the controlling element is electrically connected to the lead frame via a metal wire. Such an IPM is in general resin-sealed by transfer molding to be formed into a sealing body.
Japanese Patent Laying-Open No. 2004-172239 describes a resin-sealed semiconductor device in which a controlling support plate is supported at a position higher than a heat sink, and a compressive force by ultrasonic thermocompression bonding is strongly applied to a connecting lead thin wire to firmly bond this connecting lead thin wire to each of a controlling element and a controlling lead terminal.